Answer: (a) Over the years there have been numerous claims

Chapter 17, Problem 17.75

(choose chapter or problem)

(a) Over the years there have been numerous claims about perpetual motion machines, machines that will produce useful work with no input of energy. Explain why the first law of thermodynamics prohibits the possibility of such a machine existing. (b) Another kind of machine, sometimes called a perpetual motion of the second kind, operates as follows. Suppose an ocean liner sails by scooping up water from the ocean and then extracting heat from the water, converting the heat to electric power to run the ship, and dumping the water back into the ocean. This process does not violate the first law of thermodynamics, for no energy is createdenergy from the ocean is just converted to electrical energy. Show that the second law of thermodynamics prohibits the existence of such a machine.